Freshwater pump keeps turning on every couple minutes

[George_SD]

Hi all,
Beneteau 323 2005 - Whenever the 12v switch for freshwater pump is on, the pump turns on for 2-4 seconds every 5 minutes or so.

My understanding that the pump should only run when there is demand for water, such as an open faucet. I think this is a pressure system, so it builds pressure and holds it until it drops (because a faucet is open) and it runs until it reaches that pressure (when faucet is closed).

I don't know if what I'm seeing is a potential sign of a leak somewhere (leaky faucet, line connection, etc)?

Freshwater tank is not pressurized as I understand, so even if the top filling cover is not sealing the tank - this should not turn on the pump, right?


Pointers?

[Island Time O25]

It is pressurized AFAIK. Could be an air leak somewhere along the hoses, connections, water heater, etc. Or if the water tanks are aluminum and many years old could be pinprick size holes from galvanic corrosion. Ask me how I know. When I one of my tanks developed a leak I found an old corroded penny under it which was the cause of the hole.

[Reefmagnet]

most likely a slow leak on the pressurised side but air being sucked from the tank, or a vacuum forming in the tank can also cause this. if its a pressure leak you would probably expect to collect water in the bilge.

[George_SD]

Tank is plastic in the bow
No water in bilge or tank compartment

Hm, i thought the pump pressurizes everything downstream from itself (hoses, faucets, etc), but the tank is not pressurized?

[rbk]

I’d check for leaks and if nothing look at the pump. Check valves and impellers do fail.

[HopCar]

You’ve got a leak. It’s that simple. If you can’t find water leaking out of the system, the valves in the pump are bad. If the valves are bad, and they all fail eventually, water will leak from the pressurized side back through the pump to the tank side.

First look for a visible leak on the pressure side. If you can’t find a leak, rebuild the pump.

[George_SD]

Alright, this sounds like a plan
1) inspect pressure side
2) inspect pump and rebuild if needed.

[Lepke]

Sometimes just a piece of debris gets stuck on the valve and holds it open slightly.

[Stewie12]

Sounds like the valves in the pressure pump. Take a look and maybe you can clean them.

[SV__Grace]

Do you have an accumulator tank? If so, test to see if it holds pressure or has a leak.

[briblack]

As far as I know, most water tanks are unpressurized, it's a suction line from the tank to the pump, and then maybe an accumulator tank (about 1 gallon) on the pressure side. If the main tank was pressurized, deck fill would be problematic

[AZUS]

HopCar has the 100% answer above. System is pressurized from the pump forward, not including the tank.

[Cheechako]

You have a micro leak somewhere between the pump and the faucets. It could be air in a high loop in the tubing, but often if it's air the pump won't shut off at all.

If you don't have an accumulator tank, yes your pump will run whenever a faucet is open. If you have an accumulator tank it will only run when the pressurized accumulator tank partially empties.

Run your hand or a piece of TP along the tubing, until it shows up wet... you've found your drip.

[Don Sloma]

My older water pump had run for hours and hours, searching for a prime. I was sure it was fried. I was all set to replace it. Then someone told me even a little bit of filth in the pump might cause a pressure leak back toward the tank. A thorough cleaning of all parts of the pump using vinegar, a soft toothbrush and a rag cured the problem. The cost was time, patience and focus. So...it was very expensive!

[Capt Clark]

George,

You may want to consider an inline pressure gauge. They are inexpensive and can narrow down the problem quickly. With all faucets off & the water pump on, you can see if there is a leak by the pressure drop. If no drop in pressure, then it’s your pump switch.

Capt Clark